]';F1' I'CT OK HKIII HEATING ON PROPERTIKS OF .AIILK 39 



(i) It ticstroys nearly all germs present in the milk. 



(2) It diminishes the viscosity, or body. 



(3) It tlri\'es olf gases. 



(4) It imparts a cooked taste fespecialh' if not heated and 

 cooled ])roi)erh'.) 



(5) It precipitates some of the albuminoids and ash constit- 

 uents. 



(6) It destroys the properties of enz}-mes present in 

 milk. 



(7) It divides or splits up the clusters and fat-globules. 

 (S) It caramelizes some of the sugar. 



1. Destroys Nearly all Germs. — Heating milk to a tempera- 

 ture of about iSo^ F. for ten minutes destroys most of the germs 

 present. This is the temperature used in most creameries for 

 pasteurization. The details concerning the different ettects of 

 temperature upon growth of germs properh' comes under the 

 heading of bacteriology, and will be referred to more in detail in 

 the chapter on " Ferments in ]Milk." 



2. Diminishes the Visc.sity, or Body. — Heating milk or 

 cream diminishes its \'iscosit},'; that is, it lessens the bod\' (jr con- 

 sistency; and in cities where milk or cream is sold directh- to 

 consumers, heated milk appears as if it had been adulterated. 

 This diminution in the bod}' is claimed to be due to a breaking 

 up of the clusters, and the fat-globules and the caseous matter. 

 The chemical union of sorne of the calcium salts and the casein 

 is altered or destroyed. 



The consistency of milk or cream can be restored by atlding 

 a substance named \'iscogcn. Russell and Babcock ' advise this 

 method of overcoming the apparent defect caused b}- heating. 

 It consists of making a strong solution of cane-sugar and mixing 

 it with freshh' slaked lime. This mixture is allowed to stand, 

 and the clear solution coming to the top is the viscogen, which, 

 when drawn off and used in the proportion of one part of viscogen 

 to from 100 to 150 parts of cream, restores its body. This is 

 due to the fact that viscogen causes the fat-globules to cluster 

 together again, and the Imie in the viscogen may combine with the 

 ' Bulletin No. 54, Wisconsin, 1896. 



